In the past, a system including a plurality of semiconductor power converting apparatuses have sometimes performed information communication among the semiconductor power converting apparatuses for the purpose of controlling the semiconductor power converting apparatuses to cooperate with one another or the other purpose like that. In performing the information communication among the semiconductor power converting apparatuses, the communication is generally performed using a dedicated communication line. However, laying man-hour for laying the dedicated communication line is substantially required. In some case, a noise current may flow via the communication line and a trouble due to noise may occur.
To solve the problem, Patent Literature 1 descries that, in a power-line carrier communication system in which a plurality of lighting apparatuses are connected to a power line, a master lighting apparatus transmits a signal to slave lighting apparatuses in a common mode communication and performs control to associate lighting states of the slave lighting apparatuses with a lighting state of the master lighting apparatus. Specifically, in the master lighting apparatus, a control unit controls a field effect transistor to be turned on and off according to a signal for controlling the lighting states of the slave lighting apparatuses and transmits a signal, which is formed according to the magnitude of the amplitude of a waveform flowing to a ground side, to the slave lighting apparatuses in the common mode communication. In the slave lighting apparatus, detection circuit extracts a signal component through a ground capacitor to form a signal of a rectangular waveform and inputs the signal to a control section, thereby receiving the signal transmitted in the common mode communication. Consequently, according to Patent Literature 1, because the signals can be transmitted and received in the common mode communication, it is, supposedly, possible to perform the power-line carrier communication without cutting off power feeding of the power line.